Application Function In A Network And Control Thereof

ABSTRACT

In a communication network with separate data planes including a control plane and a user plane, an application function is provided as a combination of an application function control plane (AF-CP) part operating in the network&#39;s control plane and an application function user plane (AF-UP) part operating in the network&#39;s user plane. The application function user plane part may be configured for the application-specific processing of user data, and instanced multiple times. The application function control plane part may be configured to support selecting an optimal instance of the application function user plane part for a particular UE.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/641,573, filed Aug. 27, 2018, which is the U.S. National Stage ofInternational Application No. PCT/EP2018/072966, filed on Aug. 27, 2018,which designates the U.S., published in English, which claims priorityunder 35 U.S.C. § 119 or 365(c) to European Application No. EP17188139.4, filed Aug. 28, 2017. The entire teachings of the aboveapplications are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a communication network comprising a pluralityof network nodes and configured to provide, as one of the networkfunctions, an application function for supporting an applicationexecuted by user equipment. The invention further relates to a networknode or a distributed system of network nodes for use in the network.The invention further relates to a method of providing the applicationfunction in the communication network, and to a computer programcomprising instructions for causing a processor system to perform themethod.

BACKGROUND ART

Next generation network architectures, such as 5G, may separate networkfunctions from the underlying hardware resources, being in the case of atelecommunication network the network nodes of the network. For thatpurpose, so-called Network Virtualization (NV) techniques may be used,and in particular Network Function Virtualization (NFV) techniques whichprovide network functions that are instantiable in software using thehardware of one or more of the network nodes.

In the following, ‘providing’ or ‘establishing’ a network function maythus comprise or refer to the instantiation of the network function inthe network.

Such next generation network architectures may further define virtualdata planes which separate data traffic in the network. Such virtualdata planes, which may be established by Software-Defined Network (SDN)but also by other techniques, may include a control plane to enabletransmission of control data in the network, and a user plane to enabletransmission of user data to and/or from User Equipment (UE) connectedto the network. The user plane may also be referred to as ‘data plane’.

Moreover, a set of virtualized network functions may be provided whichmay be instantiable using one or more of the plurality of network nodesand which comprise user plane functions operating in the user plane andcontrol plane functions operating in the control plane. For example,such control plane functions may include a Session Management Function(SMF) configured to select one or a linked series of user planefunctions to be used in a data communication session involving the UE.

Another design target of next generation network architectures is toprovide networks which will be ‘tailored’ to the requirements of theapplications which use the network. Such ‘tailoring’ to a specific typeof application, for example a video application running on the UE, mayinvolve the network providing one or more Application Functions (AFs)which provide functions such as streaming of video content, transcodingof the video content, storage of the video content, synchronization ofthe video content, etc. Effectively, an AF may, when instantiated in thenetwork, configure one or a distributed system of network nodes tofunction as a streaming server, a transcoder, a network cache, a streamsynchronizer, etc. There may be several instantiations of such AF, e.g.,to achieve a geographic distribution.

It is noted that although the above refers to virtualization of dataplanes and network functions, it is also known to establish the dataplanes and the network functions as described in this specificationwithout virtualization techniques.

3GPP [1] (see references at end of section) describes an architecturefora next generation mobile network which includes AFs. Thisarchitecture is shown in FIG. 1, where the AF is shown to beinstantiated as a control plane function operating in the Control Plane(CP) of the network. However, the AF in this architecture may be seen asmerely representing a function placeholder for different applicationsand having only broadly defined procedures for how applications caninfluence the network traffic.

Ericsson [2] proposes to provide the AF in a Content Delivery Network(CDN), with the AF being connected to the UPF via the N6 interface. TheAF is thereby similar to a traditional proxy cache except now beinglocated at the mobile edge. Accordingly, the decision of whether the UEwill use a certain AF instance may be made by the ‘request routing’functionality of the CDN which is typically located far from the UE'sAccess Network (AN). This may have a number of disadvantages:

-   -   Request routing may introduce latency. For example, the first        request of the UE may be sent outside the access and core        network, resulting in a higher latency than a request which is        directly sent to an edge cache. In fact, it may require the UE        to send one extra message to receive the requested data since        the UE may first send the request to the central CDN ‘request        routing functionality’ which may reply with the AF's address        that is to be used in the subsequent request message    -   Selection of AF instances may not be optimal. Although the CDN        can also obtain information about the UE's mobility via the        connection of the AFs to the Network Exposure Function (NEF),        the level of exposure which is provided by the NEF to the        information on the AF and other network functions is less than        what the network functions offer themselves: the NEF may lack        knowledge which may result in the CDN making a sub-optimal        selection. For example, an AF may be selected which seems closer        to the UE, but which in reality is not due to how the user data        is routed.    -   More complexity in the CDN ‘request routing’ functionality. In        an attempt to obtain optimal AF selection, the CDN may have to        take aspects into account which may be essentially internal to        the network, such as mobility events, degradation events, etc.        This may not only make the CDN's routing more complex, but also        this type of information may mismatch the CDN operating (mostly)        at the application layer.

REFERENCES

-   [1] 3rd Generation Partnership Project, Technical Specification    Group Services and System Aspects, “System Architecture for the 5G    System, Stage 2 (Release 15)”, TS 23.501 V1.0.0 (2017-06)-   [2] Ericsson LM, “Use-cases for 5G Media Distribution”, Tdoc    SA-170569, Jun. 26-30, 2017.

SUMMARY OF THE INVENTION

It would be desirable provide an application function in a communicationnetwork which addresses one or more of the disadvantages of [1] or [2].

The following aspects of the invention involve providing an applicationfunction which may be provided as a combination of an applicationfunction control plane part operating in the control plane and anapplication function user plane part operating in the user plane. Theapplication function user plane part may be configured for theapplication-specific processing of user data associated with theapplication, and instanced multiple times. This partitioning of theapplication function may address one or more of the disadvantages of [1]or [2], since the control part may be provided in the control plane ofthe network, and thereby in the core of the network, and configured tosupport selecting an ‘optimal’ instance of the user plane part for aparticular UE.

In accordance with a first aspect of the invention, a communicationnetwork may be provided which may comprise a plurality of network nodes.

The network may be configured to provide:

-   -   a control plane to enable transmission of control data in the        network;    -   a user plane to enable transmission of user data to and/or from        user equipment which is connected to the network; and    -   a set of network functions which may comprise user plane        functions operating in the user plane and control plane        functions operating in the control plane.

The control plane functions may include a session management functionconfigured to select, and optionally configure one or a linked series ofuser plane functions to be used in a data communication sessioninvolving the user equipment.

The network may be configured to provide, as one of the networkfunctions, an application function which supports an applicationexecuted by the user equipment, the application function being providedas a combination of an application function control plane part operatingin the control plane and an application function user plane partoperating in the user plane and configured for application-specificprocessing of user data associated with the application.

The application function user plane part may be selected from aplurality of application function user plane parts, each of theplurality of application function user plane parts being accessible viaone or more user plane functions.

The application function control plane part may be configured withidentification information identifying the plurality of applicationfunction user plane parts and to communicate with the session managementfunction to enable said function to select the one or the linked seriesof user plane functions so as to establish a network path from the userequipment to said selected application function user plane part.

In accordance with a further aspect of the invention, a network node ora distributed system of network nodes may be configured as theapplication function control plane part in the communication network andmay comprise:

-   -   a data storage comprising the identification information        identifying the plurality of application function user plane        parts;    -   a network interface to the network;    -   a processor system configured to communicate via the network        interface with the session management function to enable said        function to select the one or the linked series of user plane        functions so as to establish the network path from the user        equipment to said selected application function user plane part.

In accordance with a further aspect of the invention, a network node ora distributed system of network nodes may be configured as theapplication function user plane part in the communication network andmay comprise:

-   -   a network interface to the network and configured to receive or        send the user data associated with the application executed by        the user equipment;    -   a processor system configured to perform the        application-specific processing of the user data.

In accordance with a further aspect of the invention, a network node ora distributed system of network nodes may be configured as the sessionmanagement function in the communication network and may comprise:

-   -   a network interface to the network and configured to receive        data from the application function control plane part which is        indicative of the selected application function user plane part,        or indicative of the network path which is to be established;

a processor system configured to, via the network interface, select theone or the linked series of user plane functions to be used in the datacommunication session involving the user equipment, wherein saidselection is based on the data received from the application functioncontrol plane part.

In accordance with a further aspect of the invention, a method may beprovided for providing an application function in a communicationnetwork. The network may comprise a plurality of network nodes and beconfigured to provide:

-   -   a control plane to enable transmission of control data in the        network;    -   a user plane to enable transmission of user data to and/or from        user equipment which is connected to the network; and    -   a set of network functions which comprise user plane functions        operating in the user plane and control plane functions        operating in the control plane.

The control plane functions may include a session management functionconfigured to select, and optionally configure one or a linked series ofuser plane functions to be used in a data communication sessioninvolving the user equipment.

The method may comprise providing, as one of the network functions, anapplication function which supports an application executed by the userequipment, the application function being provided as a combination ofan application function control plane part operating in the controlplane and an application function user plane part operating in the userplane and configured for application-specific processing of user dataassociated with the application, wherein the application function userplane part is a selected one of a plurality of application function userplane parts being accessible via one or more user plane functions.

Providing the application function may comprise:

-   -   configuring the application function control plane part with        identification information identifying the plurality of        application function user plane parts;    -   selecting the application function user plane part from the        plurality of application function user plane parts; and    -   establishing communication between the application function        control plane part and the session management function to enable        said function to select the one or the linked series of user        plane functions so as to establish a network path from the user        equipment to said selected application function user plane part.

The above measures may be based on the following considerations. It maybe desirable to enable an application running on an UE to use an‘optimal’ AF instance amongst the AF instances in a network. Here,‘optimal’ may refer a global optimum but also a local optimum, e.g.,being better than another AF selection. Such ‘optimality’ may bequantifiable by one or a combination of network metrics, or in terms ofmeeting requirements such as application requirements, etc. Variousother quantifications of ‘optimality’ are equally conceived. It may alsobe desirable to provide the application function in a manner which istransparent to the application, e.g., to avoid CDN vendors and/orservice providers having to deal with low-level, network-layer details.

The application function as provided by the above measures may representa partitioning in two parts: a part that performs the actualapplication-specific processing of the user data, which may be referredto as Application Function—User Plane (AF-UP), and a part that controlsthe usage of the application function, which may be referred to asApplication Function-Control Plane (AF-CP). The AF-CP may be provided inthe control plane of the network, and thereby in the core of thecommunication network, rather than outside of the core network, e.g., ina data network such as the CDN. There may be several AF-UP instances,for example representing different edge caches, with each of these AF-UPinstances being connected to the core network via one or more UPFs. TheUPFs may transmit and process user data in a non-application specificmanner, and may be selected and optionally configured by the SMF whenestablishing a data communication session involving the UE. The AF-CPmay be aware of these AF-UPs, e.g., in terms of their network address,location, application-specific capabilities, etc., e.g., by way ofidentification information stored by the AF-CP. With this identificationinformation, the AF-CP may support the SMF in selecting one or more UPFswhich represent an optimal network path to a desired AF-UP, e.g., bysending data to the SMF indicative of the AF-UP or the network pathwhich is to be established to the AF-UP. This desired AF-UP may bedirectly selected by the AF-CP. Alternatively, the SMF may select one ormore UPFs which lead to, and thereby essentially select, a particularAF-UP.

For example, in some embodiments, the AF-UP may be selected to belocated close(st) to the UE, in order to save network bandwidth anddecrease latency. This may enable new network services, e.g., whereultra-low latency may be required, such as Virtual Reality (VR) orAugmented Reality (AR), and may improve the performance of existingservices, e.g., video streaming in a highly mobile environment.

In line with 3GPP [1], it is envisioned that the AF-CP may be ‘internal’or ‘external’ to the core of the network. In the first case, the AF-CPmay be directly connected to a service bus of the control plane. In thelatter case, the AF-CP may be connected to the NEF and interact withother control functions via the NEF.

In an embodiment, the application function control plane part may beconfigured to select the application function user plane part, andprovide data indicative of the selected application function user planepart, or indicative of the network path which is to be established, tothe session management function to enable said function to select theone or the linked series of user plane functions to the selectedapplication function user plane part. The AF-CP may thus select theAF-UP and may ‘steer’ the SMF to establish a suitable network path tothe AF-UP by providing data to the SMF which is indicative of theselected AF-UP, e.g., of its exact or approximate location, or datawhich is indicative of the network path to be established to theselected AF-UP.

For example, the data provided to the session management function maycomprise network-level information, including but not limited to one ormore of:

-   -   an identifier indicative of the application function user plane        part, e.g., a type allocation code identifier;    -   a location of the application function user plane part, e.g., as        indicated by a cell identifier;    -   an identifier of the user equipment;    -   an identifier or a serving area of one or more of the selected        one or linked series of user plane functions; and    -   a data network name of a data network which comprises the        application function user plane part.

In another example, the data provided to the session management functionmay comprise application-level information, including but not limited toone or more of:

-   -   an identifier of the application; and    -   an identifier of the application-specific processing to be        performed by the selected application function user plane part.

In an embodiment, the application function control plane part may beconfigured to identify a subset of the plurality of application functionuser plane parts, and provide data indicative of the subset ofapplication function user plane parts, or data indicative of the networkpath which is to be established to one or more of the subset, to thesession management function. The session management function may beconfigured to select the one or the linked series of user planefunctions based on said data. Instead of directly selecting oneparticular AF-UP, the AF-CP may rather influence the SMF to select froma subset of AF-Ups. For example, the AF-CP may identify a subset ofsuitable AF-UPs, e.g., which all meet certain application requirements,and identify these AF-UPs to the SMF, e.g., in the form of thenetwork-level or application-level information as previously described.An advantage of this embodiment is that the SMF may also take otherconsiderations into account, such as network conditions, load, topology,etc., which may represent a more ‘holistic’ approach to the selection ofthe AF-UP than the direct selection of the AF-UP by the AF-CP.

In an embodiment, the session management function may be configured to,when selecting a linked series of user plane functions, select an accessuser plane function which is connected to an access network, via whichthe user equipment is connected to the network, on the basis of theaccess user plane function having at least one of: a serving area whichincludes the user equipment, and a location nearest to the userequipment according to a distance metric. The SMF may thus select theseries of UPFs to have an access UPF nearby the access network of theUE. This may provide a lower latency and/or higher bandwidth between theUE and the AF-UP.

In an embodiment, the control plane functions of the network may furtherinclude a policy function which performs policy control for quality ofservice in the network, and the session management function may beconfigured to select the one or the linked series of user planefunctions further based on policy data provided by the policy function.In an embodiment, the application function user plane part may beselected further based on the policy data. By taking the policy data inaccount, the UPFs and/or the AF-UP may be selected to achieve betterquality of service.

In an embodiment, the control plane functions of the network may furtherinclude an access management function for authenticating and authorizinguser equipment so as to enable the user equipment to register with thenetwork, and the application function control plane part may beconfigured to subscribe to the access management function with a list ofidentifiers of user equipment so as to be notified when the userequipment identified on the list registers with the network. This mayallow the AF-CP to initiate the selection of an AF-UP and associatedUPF(s) when a UE, which may be known to run an application, registerswith the network.

In an embodiment, the access management function may be furtherconfigured to manage mobility of the user equipment and signal theapplication function control plane part when the user equipment changeslocation.

In a specific embodiment which further illustrates the advantages ofseveral of the above measures, a UE may request a Protocol Data Unit(PDU) session with a 3GPP/5G network for a specific application. The SMFmay use locality information from an Access and Mobility ManagementFunction (AMF), policy data from a Policy Function (PCF) andapplication-level and/or network-level information from the AF-CP, toselect the optimal UPF(s) and build a PDU session for the UE to aselected AF-UP.

In a more specific embodiment, the AF-UP may be selected at the time ofestablishment of the UE's PDU session. Accordingly, it may be avoidedthat time is unnecessarily spent to establish a first PDU session to aCDN request routing function outside the 3GPP/5G network, and thenestablish a second PDU session to a local AF. The SMF may also know thetopology and traffic conditions of the network, which may furthercontribute to the optimality of the selected UPF(s). In a more specificembodiment, the SMF may dynamically reroute the PDU session to anotherUPF during a PDU session, e.g., if network conditions, load, topology orapplication requirements change. This may allow for a more granularcontrol of the AF resources.

In an embodiment, the communication network be a telecommunicationnetwork. In an embodiment, the communication network may comprise a corenetwork, e.g., of a mobile network. In an embodiment, the communicationnetwork may be a network adhering to one or more 3GPP standards.

In an embodiment, the application function may be a media function, andthe application-specific processing performed by the applicationfunction user plane part may be a processing of media content, includingbut not limited to one or more of:

-   -   a streaming of the media content;    -   a transcoding of the media content;    -   a storage of the media content; and    -   a synchronization of the media content.

It will be appreciated by those skilled in the art that two or more ofthe above-mentioned embodiments, implementations, and/or aspects of theinvention may be combined in any way deemed useful.

Modifications and variations of any one of the network nodes, the methodand/or the computer programs, which correspond to the describedmodifications and variations of the communication network, may becarried out by a person skilled in the art on the basis of the presentdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter. Inthe drawings,

FIG. 1 shows a prior art telecommunication network in which an AF isprovided as a control plane function operating in the control plane ofthe network;

FIG. 2 shows a telecommunication network in which an AF is provided as acombination of a control plane part (AF-CP) and a user plane part(AF-UP);

FIG. 3 shows the telecommunication network of FIG. 2 with multiple AF-UPinstances, each being connected to a respective user plane function(UPF);

FIG. 4 illustrates message exchange during setup of the AF, with theAF-CP registering with several network functions for events that involveselected UEs;

FIG. 5 illustrates a further message exchange during the setup of theAF, with the AF-CP being informed of location information related to theUE;

FIG. 6 illustrates a message exchange in the establishment of a PDUsession, showing messages from initial UE request to SMF notification;

FIG. 7 illustrates a further message exchange in the establishment ofthe PDU session, involving the selection of UPFs by the SMF;

FIG. 8 illustrates a further message exchange in the establishment ofthe PDU session, involving the PCF, AMF and UE being notified of PDUsession details;

FIG. 9 illustrates a traffic flow during the established PDU session;

FIG. 10 illustrates a message exchange following a UE location change;

FIG. 11 shows a network node implementing an AF-CP;

FIG. 12 shows a network node implementing an AF-UP;

FIG. 13 shows a method of providing an application function;

FIG. 14 shows a computer readable medium comprising non-transitory datacomprising instructions for causing a processor system to perform themethod; and

FIG. 15 shows an exemplary data processing system.

It should be noted that items which have the same reference numbers indifferent figures, have the same structural features and the samefunctions, or are the same signals. Where the function and/or structureof such an item has been explained, there is no necessity for repeatedexplanation thereof in the detailed description.

LIST OF REFERENCE AND ABBREVIATIONS

The following list of references and abbreviations is provided forfacilitating the interpretation of the drawings and shall not beconstrued as limiting the claims.

-   -   N1-N6 interfaces    -   AF application function    -   AF-CP application function control plane part    -   AF-UP application function user plane part    -   AMF access management function    -   CDN content delivery network    -   CP control plane    -   DN data network    -   DNN data network name    -   NEF network exposure function    -   PCF policy function    -   PDU protocol data unit    -   (R)AN (radio) access network    -   SMF session management function    -   SUPI subscriber permanent identifier    -   UE user equipment    -   UP user plane    -   UPF user plane function    -   0′, 0″ notification request (SUPI list, mobility events)    -   0′″ notification request (SUPI list)    -   1 registration    -   2, 2′ notification (UE registered, location)    -   3 PDU session establishment request (DNN of CDN, slice)    -   4 selection of SMF in slice    -   5 PDU session establishment request (DNN of CDN)    -   6 notification request (location change)    -   7, 7′, 7″ PDU session establishment messages    -   8, 9 PDU session establishment response    -   10, 10′, 10″ notification request (IP address change)    -   11, 11′, 11″ notification (IP address of UE)    -   12 traffic flow    -   13 notification (UE location change)    -   14 change access UPF    -   15, 15′, 15″ request for AF-UP information    -   100 network configured to provide application function    -   110 service bus    -   200 network node configured as AF-CP    -   210 network interface    -   220 processor    -   230 storage    -   300 network node configured as AF-UP    -   310 network interface    -   320 processor    -   400 method of providing application function    -   410 providing application function as combination of parts    -   420 configuring application function control plane part    -   430 selecting application function user plane part    -   440 selecting user plane functions    -   500 computer readable medium    -   510 non-transitory data    -   1000 exemplary data processing system    -   1002 processor    -   1004 memory element    -   1006 system bus    -   1008 local memory    -   1010 bulk storage device    -   1012 input device    -   1014 output device    -   1016 network adapter    -   1018 application

DETAILED DESCRIPTION OF EMBODIMENTS

The following embodiments are described in the context of atelecommunication network adhering to one or more 5G 3GPP standards,such as [1] which is hereby incorporated by reference. In theseembodiments, the network functions as claimed may be further explainedin accordance with the following glossary. This glossary, however, isnot meant to limit the interpretation of the claims. Namely, theconcepts described in the following embodiments may equally apply,mutatis mutandis, to any other type of communication network havingseparate user and control planes and network function capable ofperforming the functions as defined by the wording of the claims.

For example, the ‘split’ AF-CP/AF-UP may be used in a communicationnetwork in the domain of Intelligent Transport Systems, mobility,self-driving cars, etc. Examples of AF-UP functions for mobility mayinclude, but not limited to:

-   -   A Road Safety server, providing, e.g., applications for        emergency vehicle warnings, intersection collision warnings and        wrong-way driving warnings;    -   A Traffic Efficiency server, providing, e.g., applications for        speed limit notifications and route guidance; and    -   A server providing further support for applications, e.g., by        providing a Local Dynamic Map.

Glossary of Terms

AMF—Access and Mobility Management Function: may provide UE-basedauthentication, authorization, and mobility management. The AMF may bethe first element that a UE connects to when it wishes to use a 5Gnetwork.

DN—Data Network: may represent a network outside of the 5G network. Thismay still be inside the operator's network, or may be outside, facingthe Internet.

NEF—Network Exposure Function: may expose the network functions andcapabilities of the 5G network to 3rd parties, e.g., not affiliated withthe operator.

PCF—Policy Function: may be responsible for policy control in order toenable Quality of Service (QoS) management.

PDU—Protocol Data Unit: this term may refer to a packet or frameexchanged between a UE and an entity in the Data Network.

PDU Session: an association between the UE and a Data Network (DN) thatprovides a PDU connectivity service. The type of association may be IP,Ethernet or unstructured. Via a PDU session the UE may exchange datawith the particular DN.

(R)AN—(Radio) Access Network: part of the network that connects the UEwith the core 5G network (e.g., AMF, PCF, NEF, SMF, UPF may be in thecore).

SMF—Session Management Function: may be responsible for sessionmanagement and may allocate IP addresses to UEs; may also select andcontrol the UPFs for data transfer; the SMF may be seen as an SDNnetwork controller.

UE—User Equipment: may represent an end-user device (e.g. mobile phone,tablet, smart watch, VR headset, TV, set-top box, laptop, etc.).

UPF—User Plane Function: may route the PDU sessions of UEs across the 5Gnetwork; it may be seen as a network router or switch or forwarder.

Prior Art Network

FIG. 1 shows a prior art telecommunication network as described by [1]in which an AF is provided as a control plane function operating in thecontrol plane CP of the network. It can be seen that the AF is connectedto a service bus 110 in the control plane CP. FIG. 1 further illustratesthe user plane UP, and interfaces N1, N2 and N4 which may be used by thecontrol plane to setup data-paths in the user plane.

Network with Partitioned AF

FIG. 2 shows a telecommunication network 100 in which an AF is providedas a combination of a control plane part AF-CP, which is connected tothe service bus 110, and a user plane part AF-UP which is connected toan UPF via a N6 interface. FIG. 3 is similar to FIG. 2, except that itshows multiple instances of AF-UPs, e.g., AF-UP₁, AF-UP₂ and AF-UP₃,which are each connected to respective UPFs, e.g., UPF₁, UPF₂ and UPF₃.Also shown is a Content Delivery Network connected to the DN. An exampleof the telecommunication network 100 is a mobile operator network whichmay contain 3GPP core functions, but also a mail server, transcoder,etc.

FIGS. 2 and 3 thus illustrate a ‘split’ AF, i.e., split into AF-CP andAF-UP, within the context of a 3GPP/5G network. Compared to the priorart 5G network of FIG. 1, the AF-CP replaces the AF in the controlplane, whereas the AF-UP is newly added. The AF-UP may be locatedoutside the 3GPP/5G network. A reason for this is that the 3GPP/5Gnetwork may be kept application-agnostic as per 5G philosophy,especially in the user plane with the UPFs in the bottom part of thefigure. The split between AF-CP and AF-UP adheres to this philosophy.Nevertheless, the AF-UP may be inside the mobile operator's network, asit may provide the practical means for the operator to improve thedelivery of media applications, e.g., with adaptively distributed localfunctions in its network, and may thus be located in the ‘mobile edge’.Also shown is the external CDN which cannot have the same deepintegration in the 5G network.

In the next sections, we describe the information exchange between thenetwork functions during or for setup of an AF, during establishment ofa PDU session, the data transfer path during the PDU session, and otheraspects such as UE mobility. Here, reference signs are provided to themessages represented by arrows in the respective figures, e.g., with (1)referring to an arrow labeled ‘1’.

AF Setup

FIG. 4 illustrates message exchange during setup of the AF, with theAF-CP registering with several network functions for events that involveselected UEs. Such setup may, in a first step, comprise the AF-CP beingset up so that it is informed when a UE registers or has a status changethat requires an action of the AF-CP/AF-UP combination. For each UE thatcan use the application (for example, because a user has a subscriptionto a media service), the AF-CP may know a unique identifier, for examplethe SUPI (Subscriber Permanent Identifier) or IMSI (International MobileSubscriber Identity). It may receive these identifiers from the CDN orapplication provider in a process not shown here. The AF-CP maysubscribe to notifications related to the involved UEs by communicatingthe list of SUPIs and the events that it is interested in to therelevant functions, including but not limited to:

-   -   PCFs (0′), for events related to policy control for QoS.    -   SMFs (0′″), for events related to the session management,        including selection of UPFs, and allocation of IP addresses to        UEs.    -   AMF (0″), for events related to UE-based authentication and        mobility.

The subscription of the AF-CP may be sent directly to the networkfunction, but also indirectly: for example, the subscription to the AMFmay be sent through the PCF as the 5G service-based architecture withits service bus allows for this. Another indirect route that may berelevant is through the NEF. This route may be appropriate when theAF-CP is, to some degree, outside of the mobile operator domain.

In the case that multiple network slices are used, the AF-CP maysubscribe to all PCFs and SMFs in the slice that it is in, and to allAMFs that serve the slice.

After the AF setup, the AF-CP may be informed of events in the 5Gnetwork that relate to the UEs and the applications for which it needsto steer the use of AF-UPs, e.g., on the basis of the AF-CPcommunicating with the SMFs.

UE Registration

FIG. 5 illustrates a further message exchange during setup of the AF,with the AF-CP being informed of location information related to the UE.Namely, as a next step, when a UE registers with the AMF and isauthenticated (1) thereby, the AF-CP may be notified. The notificationmay take different routes: directly from the AMF to the AF-CP, see (2)solid line, through the PCF, see (2), (2′) dotted lines, or through theNEF (not shown in the picture).

PDU Session Establishment

FIG. 6 illustrates a message exchange in the establishment of a PDUsession, comprising messages from initial UE request to SMFnotification. Once the UE has received the necessary information duringregistration, it may be ready to initiate a PDU session with the networkfor the particular service the UE intends to use. Hence, the UE mayissue a PDU Session establishment request (3) to the AMF, whileproviding information received during registration, such as the DNN ofthe CDN and the slice ID. The AMF may select (4) one of the SMFs in theslice that the UE is deemed to use, and may then forward (5) the PDUsession establishment request to the selected SMF (5). The SMF maysubscribe (6) to the AMF for a change of the location of this UE, incase such location change would require changing traffic paths for thisUE. This may correspond to standard procedure in a 3GPP/5Gtelecommunication network.

FIG. 7 illustrates a further a message exchange in the establishment ofthe PDU session, but now involving the selection of UPFs by the SMF.Namely, at this point, the SMF may select the chain of UPFs for this UE.To do so, the SMF may obtain information from the AF-CP, e.g.,associated with the AF-UP to route the PDU session to, and optionallyfrom the PCF, e.g., regarding QoS requirements of this UE. To obtainthis information, there are several messaging possibilities, including:

1. The SMF may ask the PCF and the AF-CP for this informationindividually, see (7) and (7′) solid lines.

2. The SMF may ask the PCF for both policy and AF-UP information; thePCF in turn may ask AF-CP for AF-UP information and, once obtained, sendboth types of information back to the SMF, see (7) and (7′) dottedlines.

3. The SMF may ask the PCF for both policy and AF-UP information; thePCF in turn may send the policy information to the AF-CP along with therequest for AF-UP information; the AF-UP may contact the SMF and provideboth policy and AF-UP information, see (7), (7′) and (7″) dot-dashedlines.

4. The SMF may ask the AF-CP for both policy and AF-UP information; theAF-CP in turn may ask the PCF for policy information and, once obtained,send both types of information back to the SMF (not shown in FIG. 7)

5. The SMF may ask the AF-CP for both policy and AF-UP information; theAF-CP in turn may send the AF-UP information to the PCF along with therequest for policy information; the PCF may contact the SPF and provideboth policy and AF-UP information (not shown in FIG. 7)

Alternatively, in otherwise the same manner as the above 5, only themessages to and from the AF-CP may be routed via the NEF (not shown inFIG. 7)

Regarding the type of information that the SMF will receive from theAF-CP for AF-UP selection, there are the several possibilities,including but not limited to:

1. The AF-CP may select which of the AF-UP instances is to be used, andpass information which directly or indirectly represents this selectionto the SMF

a. This information may be network-level information, e.g., TAC ID, cellID, UPF ID, UPF serving area, DNN of where the designated AF-UP islocated, and/or

b. This information may be application-level information, e.g., “Netflixcache”, “Facebook transcoder”, “YouTube stream synchronizer”

2. The AF-CP may send a list of AF-UP instances to the SMF that can beused, e.g., in the form of the same information as above, and the SMFmay make the selection of UPF(s) related to the most appropriate one.

In general, the AF-CP may select one or more AF-UPs based on thefunctions needed by the application, being for example caching,transcoding, etc. The function may also be highly application-specific,e.g., a ‘Netflix’ cache. The AF-CP may be aware of the AF-UPs andthereby the available functions, or may in some embodiments beconfigured to establish a new AF-UP to perform a desired function. Inselecting one or more of the AF-UPs, geographical information may beused, which may be represented by network-level information. The AF-CPmay provide data to the SMF which may be indicative of the selectedAF-UPs, such as exit ports of UPFs, locations, IDs that make it clearfor the SMF how to route to the AF-UPs, etc. For example, the AF-CP maysignal data such as ‘interface XYZ on UPF at location ABC/withidentifier FEG’ to the SMF. The SMF may combine this data from the AF-CPwith other information it has on the overall network architecture toselect the UPF chain.

In either case, the access (or entry) UPF, referring to the first UPFthat the traffic from the UE to the AF-UP instance or CDN traverses, maybe selected by the SMF using network information (e.g., user location),which may be a 3GPP standard procedure. However, unlike the standardprocedure, the anchor (or exit) UPF, referring to the last UPF traversedby the traffic from the UE to the AF-UP instance or CDN, may eitherselected by the AF-CP (option 1 above) or selected by the SMF (option 2above in combination with standard procedure) based on information fromthe AF-CP.

FIG. 8 illustrates a further a message exchange in the establishment ofthe PDU session, involving the PCF, AMF and UE being notified of PDUsession details. Namely, after the AF-CP has provided information to theSMF, it may subscribe to the SMF in order to be notified of the IPaddress that the SMF may assign to the UE following the selection of thechain of UPFs. This subscription may be issued by the AF-CP directly tothe SMF, see solid line (10), or via the PCF, see dotted lines (10′),(10″), or via the NEF (not shown in this Figure). Once the SMF hasselected the chain of UPFs for the PDU session of the particular UE inquestion, the SMF may notify the AF-CP of the IP address assigned to theUE. This notification may be directly sent by the SMF to the AF-CP, seesolid line (11), or via the PCF, see dotted lines (11′), (11″), or viathe NEF (not shown in this Figure). Furthermore, the SMF may inform theAMF that the PDU session establishment is accepted via a message (8) tothe AMF. The AMF in turn may inform the UE via a message (9).

PDU Session

FIG. 9 illustrates a traffic flow via the established PDU session. Oncethe UE has received confirmation that the PDU session is established,the UE may start sending data over the network. In the example of FIG.9, the AF-UP handling the traffic from the UE may be an ‘edge cache’caching a video stream, and the network, based on the mechanismsintroduced in the previous section, may have selected the AF-UP₂instance and thereby UPF₂. The UE may thus use the PDU session toconnect to AF-UP₂, request the video stream and then receive it fromAF-UP₂, see (12) in FIG. 9.

UE Location Change

FIG. 10 illustrates a message exchange following a UE location change.Namely, as the UE moves, it may fall outside of the serving area of theaccess UPF that it is currently using. The new UE location may becommunicated (13) by the AMF to the SMF and AF-CP. The latter type ofcommunication, although not shown in FIG. 10, may involve the SMFtriggering the AF-CP, e.g., based on a previous policy input from thePCF or AF-CP, or the AF-CP receiving a notification from the AMF upon UEmobility and issuing a request to the SMF to change the anchor UP. Thisin turn may result in the SMF changing the anchor UPF (14). The SMF maythen request the AF-CP again for AF-UP information, either directly, seesolid line (15′), or indirectly via the PCF, see dash-dotted lines (15),(15′), (15″) in which the request is sent via the PCF but the AF-CPresponds directly to the SMF or dotted lines (15), (15′), (15″) in whichthe AF-CP responds via the PCF, or via the NEF (not shown in thefigure).

This may essentially be a repetition of parts of the steps/messages asshown in FIG. 7 in the PDU session establishment, with a differencebeing that requesting policy information from the PCF again may not beneeded. The outcome of this step may be a new chain of UPFs for the UE'sPDU session, in which the access UPF has changed and possibly the anchorUPF too, e.g., to a nearer UPF (e.g. UPF₃). Once the new anchor UPF hasbeen established, the AF-CP may be notified of the new IP addressallocated to the UE, if the IP address indeed has changed.

Changes in AF-UPs

After a PDU session has been established, it may occur that new AF-UPinstances are deployed in the network, or that current instances arewithheld (e.g., switched off or become unavailable). When this happens,the AF-CP may be informed using a known mechanism and may trigger theSMF to re-determine the UPF chain, as described in the previous section,for at least all UEs being served by a AF-UP that has been withheld,and/or for at least all UEs that may be affected by a new AF-UP instancebeing introduced, e.g., UEs in the proximity of the new AF-UP instance.

PDU Session Termination

It is noted that the partitioning of the AF function does not affect PDUsession termination mechanisms. The AF-CP may be notified that the UEhas terminated the PDU session, e.g., via a subscription with the AMF.

FIG. 11 shows a more detailed view of the AF-CP 200, being in thisexample embodied by a single network node. It can be seen that the AF-CP200 may comprise a network interface 210 for communicating with othernetwork nodes in the network. The network interface 210 may take anysuitable form, including but not limited to a wired network interfacebased on Ethernet or optical fiber or a wireless network interface. FIG.11 further shows the AF-CP 200 comprising a storage 230, such as a harddisk, a solid state drive, or an array thereof, which may compriseidentification information identifying one or more AF-UPs provided inthe network.

The AF-CP 200 may further comprise a processor 220 which may beconfigured, e.g., by hardware design or software, to perform theoperations described with reference to FIG. 2-10 in as far as pertainingto the AF-CP. For example, the processor 220 may be embodied by a singleCentral Processing Unit (CPU), but also by a combination or system ofsuch CPUs and/or other types of processing units.

In general, the AF-CP 200 may be embodied by a (single) device orapparatus. For example, the AF-CP 200 may be embodied by a singlenetwork node, e.g., a network server. The AF-CP 200 may also be embodiedby a distributed system of such devices or apparatuses. An example ofthe latter may be the functionality of the AF-CP 200 being distributedover different network nodes of a network.

FIG. 12 shows a more detailed view of the AF-UP 300, being in thisexample embodied by a single network node. It can be seen that the AF-UP300 may comprise a network interface 310 for receiving and sending datasuch as (processed) user data. The network interface 310 may take anysuitable form, including but not limited to those described withreference to the network interface 210 of the AF-CP 200 of FIG. 11.

The AF-UP 300 may further comprise a processor 320 which may beconfigured, e.g., by hardware design or software, to perform theoperations described with reference to FIG. 2-10 and others in as far aspertaining to the AF-UP. For example, the processor 320 may be embodiedby a single Central Processing Unit (CPU), but also by a system of suchCPUs and/or other types of processing units. Although not shown in FIG.12, the AF-UP 300 may further comprise a storage, e.g., for use incaching of storage functions. The storage may be of a same or similartype as the storage of the AF-CP 200 as previously described withreference to FIG. 12.

In general, the AF-UP 300 may be embodied by a (single) device orapparatus. For example, the AF-UP 300 may be embodied by a singlenetwork node, e.g., a network server. The AF-UP 300 may also be embodiedby a distributed system of such devices or apparatuses. An example ofthe latter may be the functionality of the AF-UP 300 being distributedover different network nodes of a network. The AF-UP 300 may be astreaming server, transcoder, storage server, stream synchronizer, etc.

Although described with reference to the AF-UP, the network node 300shown in FIG. 12 may also, in terms of architecture, represent a SMF. Inthis case, the network interface 310 may be configured to receive datafrom the AF-CP which is indicative of one or more AF-UPs, or indicativeof the network path which is to be established, and the processor 320may be configured to, via the network interface 310, select andoptionally configure the one or the linked series of UPFs to be used inthe data communication session involving the UE, wherein said selectionis based on the data received from the AF-CP. The SMF may comprise astorage, e.g., for maintaining state information on the network andnetwork sessions. The storage may be of a same or similar type as thestorage of the AF-CP 200 as previously described with reference to FIG.12. The SMF may be embodied by a single network node but also by adistributed system of network nodes, as also described above for theAF-UP.

In general, the AF-CP 200 of FIG. 11 and the AF-UP 300 of FIG. 12 or theSMF may each be embodied as, or in, a device or apparatus. The device orapparatus may comprise one or more (micro)processors which executeappropriate software. The processors of either system may be embodied byone or more of these (micro)processors. Software implementing thefunctionality of either system may have been downloaded and/or stored ina corresponding memory or memories, e.g., in volatile memory such as RAMor in non-volatile memory such as Flash. Alternatively, the processorsof either system may be implemented in the device or apparatus in theform of programmable logic, e.g., as a Field-Programmable Gate Array(FPGA). Any input and/or output interfaces may be implemented byrespective interfaces of the device or apparatus, such as a networkinterface. In general, each unit of either system may be implemented inthe form of a circuit. It is noted that either system may also beimplemented in a distributed manner, e.g., involving different devices.

FIG. 13 shows a method 400 of providing an application function. Themethod 400 may correspond to an operation of the network, or one or morenetwork nodes thereof, described with reference to FIGS. 2-12. However,this is not a limitation, in that the method 400 may also be performedby another entity or distributed system of entities. The method 400 maycomprise, in an operation 410 titled ‘PROVIDING APPLICATION FUNCTION ASCOMBINATION OF PARTS’, providing, as one of the network functions, anapplication function which supports an application executed by the userequipment, the application function being provided as a combination ofan application function control plane part operating in the controlplane and an application function user plane part operating in the userplane and configured for application-specific processing of user dataassociated with the application, wherein the application function userplane part is a selected one of a plurality of application function userplane parts being accessible via one or more user plane functions.

The providing 410 the application function may comprise, in an operationtitled ‘CONFIGURING APPLICATION FUNCTION CONTROL PLANE PART’,configuring 410 the application function control plane part withidentification information identifying the plurality of applicationfunction user plane parts. The providing 410 the application functionmay further comprise, in an operation titled ‘SELECTING APPLICATIONFUNCTION USER PLANE PART’, selecting 420 the application function userplane part from the plurality of application function user plane parts.The providing 410 may further comprise, in an operation titled‘SELECTING USER PLANE FUNCTIONS’, establishing communication between theapplication function control plane part and the session managementfunction to enable said function to select 430 the one or the linkedseries of user plane functions so as to establish a network path fromthe user equipment to said selected application function user planepart.

It will be appreciated that the above operations may be performed in anysuitable order, e.g., consecutively, simultaneously, or a combinationthereof, subject to, where applicable, a particular order beingnecessitated, e.g., by input/output relations.

The method 400 may be implemented on a processor system, e.g., on acomputer as a computer implemented method, as dedicated hardware, or asa combination of both. FIG. 14 shows a computer-readable medium 500. Forexample, instructions for the processor system, e.g., executable code,may be stored on the computer readable medium 500, e.g., in the form ofa series 510 of machine readable physical marks and/or as a series ofelements having different electrical, e.g., magnetic, or opticalproperties or values. The executable code may be stored as transitory ornon-transitory data. Examples of computer readable mediums includememory devices, optical storage devices, integrated circuits, onlinesoftware, etc.

FIG. 15 is a block diagram illustrating an exemplary data processingsystem that may be used in the embodiments described in thisspecification. Such data processing systems include data processingentities described in this specification, including but not limited tothe AF-CP, the AF-UP and the SMF.

The data processing system 1000 may include at least one processor 1002coupled to memory elements 1004 through a system bus 1006. As such, thedata processing system may store program code within memory elements1004. Further, processor 1002 may execute the program code accessed frommemory elements 1004 via system bus 1006. In one aspect, data processingsystem may be implemented as a computer that is suitable for storingand/or executing program code. It should be appreciated, however, thatdata processing system 1000 may be implemented in the form of any systemincluding a processor and memory that is capable of performing thefunctions described within this specification.

Memory elements 1004 may include one or more physical memory devicessuch as, for example, local memory 1008 and one or more bulk storagedevices 1010. Local memory may refer to random access memory or othernon-persistent memory device(s) generally used during actual executionof the program code. A bulk storage device may be implemented as a harddrive, solid state disk or other persistent data storage device. Theprocessing system 1000 may also include one or more cache memories (notshown) that provide temporary storage of at least some program code inorder to reduce the number of times program code must be retrieved frombulk storage device 1010 during execution.

Input/output (I/O) devices depicted as input device 1012 and outputdevice 1014 optionally can be coupled to the data processing system.Examples of input devices may include, but are not limited to, forexample, a microphone, a keyboard, a pointing device such as a mouse, agame controller, a Bluetooth controller, a VR controller, and a gesturebased input device, or the like. Examples of output devices may include,but are not limited to, for example, a monitor or display, speakers, orthe like. Input device and/or output device may be coupled to dataprocessing system either directly or through intervening I/Ocontrollers. A network adapter 1016 may also be coupled to dataprocessing system to enable it to become coupled to other systems,computer systems, remote network devices, and/or remote storage devicesthrough intervening private or public networks. The network adapter maycomprise a data receiver for receiving data that is transmitted by saidsystems, devices and/or networks to said data and a data transmitter fortransmitting data to said systems, devices and/or networks. Modems,cable modems, and Ethernet cards are examples of different types ofnetwork adapter that may be used with data processing system 1000.

As shown in FIG. 15, memory elements 1004 may store an application 1018.It should be appreciated that data processing system 1000 may furtherexecute an operating system (not shown) that can facilitate execution ofthe application. The application, being implemented in the form ofexecutable program code, can be executed by data processing system 1000,e.g., by processor 1002. Responsive to executing the application, thedata processing system may be configured to perform one or moreoperations to be described herein in further detail.

In one aspect, for example, data processing system 1000 may representthe AF-CP. In that case, application 1018 may represent an applicationthat, when executed, configures data processing system 1000 to performthe functions described herein with reference to the AF-CP. In anotheraspect, data processing system 1000 may represent the AF-UP. In thatcase, application 1018 may represent an application that, when executed,configures data processing system 1000 to perform the functionsdescribed herein with reference to the AF-UP. In another aspect, dataprocessing system 1000 may represent the SMF. In that case, application1018 may represent an application that, when executed, configures dataprocessing system 1000 to perform the functions described herein withreference to the SMF.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. Use of the verb “comprise” and itsconjugations does not exclude the presence of elements or steps otherthan those stated in a claim. The article “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention may be implemented by means of hardware comprising severaldistinct elements, and by means of a suitably programmed computer. Inthe device claim enumerating several means, several of these means maybe embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. A communication network comprising a plurality of network nodes, thenetwork configured to provide: a control plane to enable transmission ofcontrol data in the network; a user plane to enable transmission of userdata to and/or from user equipment which is connected to the network;and a set of network functions which comprise user plane functionsoperating in the user plane and control plane functions operating in thecontrol plane, wherein the control plane functions include a sessionmanagement function configured to select one or a linked series of userplane functions to be used in a data communication session involving theuser equipment; wherein the network is configured to provide, as one ofthe network functions, an application function which supports anapplication executed by the user equipment, the application functionbeing provided as a combination of an application function control planepart operating in the control plane and an application function userplane part operating in the user plane and configured forapplication-specific processing of user data associated with theapplication, wherein: the application function user plane part isselected from a plurality of application function user plane parts, eachof the plurality of application function user plane parts beingaccessible via one or more user plane functions; and the applicationfunction control plane part is configured with identificationinformation identifying the plurality of application function user planeparts and to communicate with the session management function to enablesaid function to select the one or the linked series of user planefunctions so as to establish a network path from the user equipment tosaid selected application function user plane part.
 2. The communicationnetwork according to claim 1, wherein the application function controlplane part is configured to: select the application function user planepart, and provide data indicative of the selected application functionuser plane part, or indicative of the network path which is to beestablished, to the session management function to enable said functionto select the one or the linked series of user plane functions to theselected application function user plane part.
 3. The communicationnetwork according to claim 1, wherein the application function partcontrol plane is configured to: identify a subset of the plurality ofapplication function user plane parts; provide data indicative of thesubset of application function user plane parts, or indicative of thenetwork path which is to be established to one or more of the subset, tothe session management function; wherein the session management functionis configured to select the one or the linked series of user planefunctions based on said data.
 4. The communication network according toclaim 1, wherein the data provided to the session management functioncomprises network-level information, including but not limited to one ormore of: an identifier indicative of an application function user planepart; a location of an application function user plane part; anidentifier of the user equipment; an identifier or a serving area of oneor more of the selected one or linked series of user plane functions;and a data network name of a data network which comprises an applicationfunction user plane part.
 5. The communication network according toclaim 1, wherein the data provided to the session management functioncomprises application-level information, including but not limited toone or more of: an identifier of the application; and an identifier ofthe application-specific processing to be performed by an applicationfunction user plane part.
 6. The communication network according toclaim 1, wherein the control plane functions of the network furtherinclude a policy function which performs policy control for quality ofservice in the network, and wherein the session management function isconfigured to select the one or the linked series of user planefunctions further based on policy data provided by the policy function.7. The communication network according to claim 6, wherein theapplication function user plane part is selected further based on thepolicy data.
 8. The communication network according to claim 1, whereinthe control plane functions of the network further include an accessmanagement function for authenticating and authorizing user equipment soas to enable the user equipment to register with the network, andwherein the application function control plane part is configured tosubscribe to the access management function with a list of identifiersof user equipment so as to be notified when the user equipmentidentified on the list registers with the network.
 9. The communicationnetwork according to claim 8, wherein the access management function isfurther configured to: manage mobility of the user equipment; and signalthe application function control plane part when the user equipmentchanges location.
 10. A network node or a distributed system of networknodes configured as the application function control plane part in thecommunication network according to claim 1, comprising: a data storagecomprising the identification information identifying the plurality ofapplication function user plane parts; a network interface to thenetwork; a processor system configured to communicate via the networkinterface with the session management function to enable said functionto select the one or the linked series of user plane functions so as toestablish the network path from the user equipment to said selectedapplication function user plane part.
 11. A network node or adistributed system of network nodes configured as the applicationfunction user plane part in the communication network according to claim1, comprising: a network interface to the network and configured toreceive or send the user data associated with the application executedby the user equipment; a processor system configured to perform theapplication-specific processing of the user data.
 12. The network nodeor the distributed system of network nodes according to claim 11,configured as at least one of: a streaming server; a transcoder; astorage server; and a stream synchronizer.
 13. A network node or adistributed system of network nodes configured as the session managementfunction in the communication network according to claim 1, comprising:a network interface to the network and configured to receive data fromthe application function control plane part which is indicative of theselected application function user plane part, or indicative of thenetwork path which is to be established; a processor system configuredto, via the network interface, select the one or the linked series ofuser plane functions to be used in the data communication sessioninvolving the user equipment, wherein said selection is based on thedata received from the application function control plane part.
 14. Amethod for providing an application function in a communication network,wherein the network comprises a plurality of network nodes and isconfigured to provide: a control plane to enable transmission of controldata in the network; a user plane to enable transmission of user data toand/or from user equipment which is connected to the network; and a setof network functions which comprise user plane functions operating inthe user plane and control plane functions operating in the controlplane, wherein the control plane functions include a session managementfunction configured to select one or a linked series of user planefunctions to be used in a data communication session involving the userequipment; the method comprising providing, as one of the networkfunctions, an application function which supports an applicationexecuted by the user equipment, the application function being providedas a combination of an application function control plane part operatingin the control plane and an application function user plane partoperating in the user plane and configured for application-specificprocessing of user data associated with the application, wherein theapplication function user plane part is a selected one of a plurality ofapplication function user plane parts being accessible via one or moreuser plane functions; wherein said providing the application functioncomprises: configuring the application function control plane part withidentification information identifying the plurality of applicationfunction user plane parts; selecting the application function user planepart from the plurality of application function user plane parts; andestablishing communication between the application function controlplane part and the session management function to enable said functionto select the one or the linked series of user plane functions so as toestablish a network path from the user equipment to said selectedapplication function user plane part.
 15. A non-transitorycomputer-readable medium comprising a computer program, the computerprogram comprising instructions for causing a processor system toperform the method according to claim 14.